Good to see links to the other solutions available. I would certainly agree that Zeus has more than other ADCs in terms of network-side scripting options.
I think "a lot less pain than iRules" really depends on your expertise and ability to grasp languages. Someone familiar with TCL or similar scripting languages will be more at ease with iRules than anything Zeus offers, while someone proficient with PHP or Java would certainly be far more comfortable with Zeus' solutions.
It's all a matter of perspective. Both are great options and I hardily encourage developers and architects alike to check out all the options and dive in.